GMC

When three truck builders – Randolph, Reliance and Rapid – merged to become GMC in 1912, the brand’s range of gasoline and electric-powered trucks used model numbers between 1 and 12, each denoting payload in thousands of pounds, or how much weight could be loaded on the rear.

GMC. A brief history.
1901. “Rapid Motor Vehicle Company” (RMVC) established, which developed the earliest commercial trucks ever designed.
1909. RMVC purchased by General Motors to form basis for the General Motors Truck Company.
1911. GM purchased Reliance Motor Car Company and merged it with RMVC.
1912. The Marque name “GMC Truck” (GMC) was first shown at the New York International Auto Show: GMC produced 372 trucks that year.
1925. GM purchases Yellow Coach, and begins manufacturing transit and inter-urban buses under the GMC nameplate until the 1980's.
1937. GMC introduced its first SUV, Suburban (later changed to Yukon); Jimmy follows in 1969.
1940s. During the Second World War, GMC produced 600,000 trucks for use by the US military.
1960. Beginning a transition from commercial to personal use vehicles, GMC introduced Sierra, the brand’s first full size personal use pick up truck.
1973. New “rounded line” truck series introduced, broadening GMC’s portfolio and creating product similarity with Chevrolet: GMCs have different trim levels, larger engine options and generally higher prices.
1980's. GMC was number three in American truck production, and compact pick up sales soared; GMC introduced its compact pick up entry the S-15.
1996. The word “truck” dropped from the GMC brand name to reflect the division’s emerging image as GM’s premium producer of trucks, vans, and sport-utility vehicles.
1998. GMC introduced its “Professional Grade” positioning to communicate the brand’s engineering excellence and innovation heritage; it’s the longest running tagline currently at GM.
2007. GMC introduced the Acadia, a crossover SUV, which is the company’s first unibody vehicle.
2009. GMC introduces the all-new Terrain, a small crossover SUV, to be the brand’s smallest vehicle to date.

(source; GM)